Equivalent parental contribution to early plant zygotic development.

Area of Science:

• Plant genetics
• Developmental biology
• Evolutionary biology

Background:

• Hybrid vigor (heterosis) arises from combining diverse genomes, impacting commercial value and biological fitness.
• Paternal genome activation typically signals a shift to zygotic control, but is often delayed in plants and animals.
• This delay has been thought to limit heterosis's influence on very early development.

Purpose of the Study:

• To investigate the timing of paternal genome activation in maize after fertilization.
• To determine if early paternal gene expression influences early embryonic development and heterosis.

Main Methods:

• Analyzed allele-specific gene expression for 25 genes post-fertilization in maize.
• Examined gene expression before the first zygotic cell division.
• Performed sequence comparisons of expressed genes.

Main Results:

• Demonstrated immediate and equivalent parental genomic contribution to the zygote.
• Found paternal transcripts present in every gene expressed before the first cell division.
• Identified these early-expressed genes as involved in diverse processes and distributed across the genome.

Conclusions:

• Maize activates the paternal genome immediately after fertilization, unlike many other species.
• This early activation strategy is consistent with high levels of heterosis observed in early maize embryos.
• The findings suggest a significant impact of this sexual strategy on early developmental fitness.